ood safety is an ubiquitous concern of both the general public and of authorities worldwide. Yet the insidious nature of mycotoxin contamination of key foods remains in many instances an of neglected area of attention. Although food-borne fungi may be capable of producing hundreds of secondary metabolites, there is a limited number of agriculturally important mycotoxins that are of particular concern due to their harmful effects on human and animal health. These are the aflatoxins, fumonisins, trichothecenes (particularly deoxynivalenol), ochratoxin A and zearalenone, which are the mycotoxins most widely regulated, although others that attract regulatory attention are patulin and ergot sclerotia.
The aflatoxins, particularly their most abundant and toxic component, aflatoxin B1, can be widely found in cereals (particularly maize) and nuts (particularly groundnuts) produced in tropical and subtropical regions. Aflatoxin B1 is a potent liver carcinogen in humans and is implicated in childhood stunting in Africa. In recent years, lethal levels of aflatoxin have caused over 100 deaths in outbreaks of poisoning in Africa. Originally discovered due to their toxicity in poultry, numerous animal studies have shown these mycotoxins to be carcinogenic, teratogenic, mutagenic and immunosuppressive. The mammalian metabolite of aflatoxin B1, aflatoxin M1, which is excreted in animal and human milk, is a concern for infants with their undeveloped gastro-intestinal and liver detoxifying systems.
The fumonisins are almost universally present in maize and maize products. They have been shown to be the causative agents for specific animal syndromes such as leukoencephalomalacia in horses, pulmonary oedema in swine and are liver and kidney carcinogens in various rodent species. In humans, the fumonisins have been associated with oesophageal cancer and neural tube defects. It has recently been suggested they play a role in childhood stunting. Human poisonings with gastro-intestinal symptoms have been reported.
The trichothecenes are a large group of mycotoxins, frequently found in cereals and co-occurring in nature. Of this group, deoxynivalenol, T-2 toxin and to a lesser extent diacetoxyscirpenol, are the main members. The former produces serious feed refusal and emetic problems in animals and has been responsible for large human toxic outbreaks with serious gastro-intestinal effects. Its immunosuppressive effects are also a cause for concern. The latter two trichothecenes are both haemorrhagic toxins that were responsible for large scale deaths from alimentary toxic aleukia in the first half of the twentieth century in the former USSR . Both these mycotoxins have been investigated as potential biological warfare agents.
Ochratoxin A can contaminate cereals and a range of other foods such as raisins, wine, coffee and spices. It is a potent kidney toxin in mammals and has been implicated in kidney cancer and the condition known as Balkan Endemic Nephropathy in Europe. Although of generally low overt toxicity, zearalenone is a naturally occurring endocrine disruptor in farm animals, particularly swine, and has been associated with endocrine problems such as precocious puberty in humans. Patulin, which can contaminated fruit juices, particularly apple juice, possesses specific antibiotic properties. Originally investigated as a potential novel antibiotic compound but rejected due to toxicity concerns, it also produces gastro-intestinal problems. Ergot alkaloids in cereals can produce both hallucinatory effects and vasoconstriction in the extremities, a condition known as ergotism, which has been well known for over five centuries in Europe.